Clutch engagement delay mechanism



Oct. 4, 1966 F. w. BERG r 3,276,561

CLUTCH ENGAGEMENT DELAY MECHANISM Filed Sept. 16, 1964 5 Sheets-Sheet 1Fig-1 INVENTOR FRED W. BERG Oct. 4, 1966 w, BERG 3,276,561

CLUTCH ENGAGEMENT DELAY MECHANISM Filed Sept. 16, 1964 5 Sheets-Sheet 2Fig- 4 INVENTOR FRED W. BERG BY 5?. t/

/ ATT RNEYS Oct. 4, 1966 w, R 3,276,561

CLUTCH ENGAGEMENT DELAY MECHANISM Filed Sept. 16, 1964 5 Sheets-$heet 3United States Patent Office 3,276,561 Patented Oct. 4, 1966 3,276,561CLUTCH ENGAGEMENT DELAY MECHANISM Fred W. Berg, West Hartford, Conn.,assignor, by mesne assignments, to Royal Typewriter Company, Inc, NewYork, N.Y., a corporation of Delaware Filed Sept. 16, 1964, Ser. No.396,990 Claims. (Cl. 197-65) This invention relates to clutch engagementdelay mechanism; more particularly it relates to clutch engagement delaymechanism characterized by an eccentric roll cam carried by a clutchactuator and operable in association with the driving element of aclutch to delay the movement of the clutch actuator to clutch engagingposition.

Line feed mechanism in present day electric typewriters is associatedwith an is operative by the carriage re turn drawband to effect indexingprior to carriage movement. In these machines a carriage return keydepression causes a carriage return clutch to engage and couple a powersource to a drawband pulley to which one end of the carriage returndrawband is secured thereby to wind the drawband. The other end of thedrawband is secured to the carriage frame on the side of the machineopposite the drawband pulley via a number of directional guide pulleys,the last of which is mounted on a spring loaded indexing lever pivotedon the carriage frame and linked by a motion transmitting spring to aratchet indexing pawl. After the indexing pawl has moved through itsworking stroke the indexing lever encounters an abutment on the carriageframe so that further pull on the drawband pulls the carriage until amargin stop on the latter encounters a carriage return clutch knockofflever adjacent the center post of the machine. When this occurs theclutch is disengaged and the platen indexing lever and pawl, since thedrawband is no longer being wound, are permitted to recover to normalposition. With the carriage returned, repeat operation of the carriagereturn key engages the carriage return clutch to index the platen andimmediately after the working stroke of the indexing mechanism theinitial movement of the carriage disengages the carriage return clutch.

In machines employing carriage return clutches characterized in that thetime between disengagement and reengagement of the clutch, incident to arepeat operation of the carriage return key, is less than the recoverytime of the platen indexing lever and pawl, care must :be taken by anoperator to insure that sufficient time has elapsed for the indexinglever to return to start position before the carriage return key isagain depressed, otherwise irregular line spacing may result.

The delay mechanism of the invention insures that a minimum time willelapse between repeat line space cycles to assure uniform spacingwithout requiring any attention on the part of the operator.

Briefly, the delay mechanism of the invention comprises a roll cameccentrically rotatably mounted on the actuator arm of a wrap springcarriage return clutch. When the arm is actuated in response todepression of a carriage return key the roll cam engages a drivingelement of the clutch and rolls about its pivot connection to theactuator arm thereby maintaining a friction or drag shoe on the actuatorarm away from the wrap spring over a predetermined interval, afterwhich, the friction shoe encounters and causes the spring to wrapthereby to couple the driving and driven elements of the clutch.

An object of the invention therefore is in the provision of mechanismresponsive to a clutch signal for delaying clutch engagement over apredetermined time interval.

Another object of the invention is in the provision of mechanism toassure full repeat cycles of line feed mechanism associated with thecarriage return mechanism of a typewriter by delaying repeat engagementof the carriage return clutch incident to repeat operation of thetypewriter carriage return key.

A further object of the invention is to provide clutch engagement delaymechanism for a wrap spring clutch which so controls engagement armcharacteristics as to reduce any bounce tendency of the clutch actuatorarm and to permit a gradual pick up of load by the clutch spring.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings in which like referencenumerals designate like parts throughout the figures thereof andwherein:

FIGURE 1 is an elevational view showing carriage return clutch actuatorelements incorporating the delay mechanism of the invention in inactivepositions;

FIGURE 2 is a cross sectional view of a power assist clutch taken alonglines 22 of FIGURE 1;

FIGURE 3 is a cross sectional view taken along lines 33 of FIGURE 1;

FIGURE 4 is an elevational view similar to FIGURE 1 showing the elementsin an active position prior to carriage return clutch engagement;

FIGURE 5 is an elevational view similar to FIGURES l and 4 showing theelements in an active position subsequent to the delay interval with thecarriage return clutch engaged;

FIGURE 6 is an elevational view showing carriage return and associatedcarriage return knockoff elements; and

FIGURE 7 is a partial elevational view showing the connection of thedrawband to the line feed indexing mechanism carried by the carriage.

Referring now to the drawings wherein like reference numerals designatelike or corresponding elements throughout the several views there isshown in FIGURE 1 a link 10 which is adapted to be driven rearwardly inresponse to depression of a carriage return key (not shown). Therearwardmost end of the link 10 is articulately connected to thedepending arm 11 of a lever 12 which is pivotally mounted on a stubshaft 13. The stub shaft as viewed in FIGURES l, 4 and 5, is rotatablysupported in an extends to either side of the right side frame 14 of themachine. The lever 12 is formed with an upwardly and rearwardlyextending arm 15 to which one end of a return spring 16 is secured; theother end being secured to an anchor pin 17 on the inner side of theright side frame thereby to return the lever 12 to the normal clutchdisengaging position of FIGURE 1. The end of the rearwardly extendingarm 15 is bifurcated with the extremities bent off to form offset upperand lower stops 21 and 22 adapted to engage a bent off end 23 of thecoil spring 24 of a wrap spring power assist clutch generally designatedby reference numeral 25 to thereby maintain the spring expanded anddisengaged from, as viewed in FIGURE 2, a driving hub 26 secured to acontinuously driven shaft 27; the other end 28 of the spring beingsecured to a driven element in the form of a circular cam 29eccentrically mounted for rotation on the driving hub.

As will be understood when the lever 12 is rocked counterclockwiseincident to depression of the carriage return key the bent off coil end23 will slide off stop 21 and wrap about the driving hub 26 coupling thelatter to the eccentric cam 29 until the coil end 23 engages a laterallyextending arm 31 of a carriage return clutch knock off lever 32 (FIGURES46) at which time, a half revolution being accomplished, the clutch 25will be disengaged. As viewed in FIGURE 2 the eccentric cam is providedwith a slot 33 through which the spring end 23 extends and which 3permits sufficient angular movement of the spring whereby it will wrapand unwrap.

The eccentric circular cam 29 is received within a circular hole 34formed in one end of a forwardly extending lever 35, whereby the initialhalf revolution movement will move lever 35 forwardly and the final halfrevolution will move lever 35 rearwardly. The lever 35 is provided witha slot 36 in its other or forward end which receives a pin 37 secured tothe upper end of a carriage return clutch actuator release lever 38which together with a clutch actuator arm 39 is keyed on stub shaft 13;the release lever 38 on the inner end and the actuator arm 39 on theouter end of stub shaft 13. A spring 41 secured to the lower end 42 ofthe actuator arm 39 and to a frame supported stud 43 biases arm 39,shaft 13, and lever 38 in counterclockwise direction to the extentpermitted by the pin and slot connection as viewed in FIG- URE 1. Thuswhen clutch 25 is engaged and lever 35 moves to the left as viewed inFIGURE 1 the clutch actuator arm 39 is committed to effect theengagement of a carriage return clutch hereinafter described.

The clutch actuator arm 33 is provided with a laterally forwardly andupwardly bent extension 44 on whose end is secured a friction or dragshoe 45 adapted to effect engagement ofa carriage return clutchgenerally designated by reference numeral 46 to connect a continuouslydriven shaft 47 to the carriage return drawband pulley 48. Moreparticularly as shown in FIGURE 3 the carriage return clutch 46comprises a hub 49 secured to the continuously driven shaft 47 whichextends axially towards a pulley hub 51 rotatably mounted on shaft 47.Both hubs are surrounded by a wrap spring 52 having one end 53 securedas by friction to the driven hub and the other end being free; thenormal diameter being such that the free end coils are spaced from thepulley hub 51. Accordingly, when the drag shoe 45, which has an arcuateshape complimentary to the spring coils, engages the coils of the freeend of the spring 52, the consequent friction slows down the free endcoils relative to the fixed end coils causing the spring to wrap andcouple hubs 49 and 51. The actuator arm extension 44 also rotatablysupports an eccentric roll cam 54 having an arcuate peripheral portion55 shaped to provide a constant, predetermined time period, sufficientfor recovery of the platen indexing mechanism, to elapse between firstcontact of the roll cam 54 and a friction drive sleeve 56, of rubber orlike material, pressed, stretched or molded in place over the end of thewrap spring adjacent the end fixed to the driving hub 49, and engagementof the clutch spring 52 by the friction shoe or drag block 45. The rollcam 54 also is provided with first and second flat peripheral portions57 and 58 at right angles to one another whereby the roll cam may bedetented in the normal inactive position of FIGURE 1 by a leaf spring 59carried by the actuator arm extension and bearing against fiat 57, andafter engagement of the arcuate portion 55 of and consequent rotation ofthe cam 54, to detent the cam 54 in a second inactive clutch engagedposition as shown in FIGURE by the spring bearing against the first flat58.

As viewed in FIGURES 6 and 7 the carriage return drawband 61 is trainedabout guide pulleys 62 and connected to the carriage frame as at 63; thelast pulley 62' in the train being rotatably carried by a line spacepawl lever arm 64 rotatably mounted on the platen shaft 65 and biased asby a spring 66 to the position shown in FIGURE 7. As the drawband 61 iswound on pulley 48, the lever arm 64 is rotated counterclockwise andthis motion is coupled to a pawl indexing lever 67, also mounted on theplatent shaft, by a motion transmitting spring 68 whereby an index pawl69 carried by lever 67 will engage the line space ratchet (not shown)and rotate the platen. After the platen is indexed a stud 71 on thelever arm 64 encounters an abutment 72 on the carriage frame so thatcontinued pull on the drawband 61 will pull the carriage.

With reference to FIGURE 6 when a margin stop 73 on the margin barcarried by the carriage encounters the margin locator or knock-offpaddle 74, pivotally secured to the center post 75 of the machine, thelocator 74 is rocked counterclockwise as viewed in FIGURE 6 and itslower end 76 pulls a link 77 toward the right thereby rocking thecarriage return knock-off lever 32 clockwise. This movement releases theend 23 of wrap spring 24 which wraps and couples the eccentric cam 29 tothe continuously driven shaft 27. After a second half revolution, theend 23 of the wrap spring will encounter stop 21 or stop 22, the latterif the carriage return key has not been released, causing the clutchspring 24 to disengage. In the latter case when the carriage return keyis released the spring end 23 will slip off stop 22 but will be engagedalmost immediately thereafter by stop 21 before the spring 24 can wrap.

The movement of the eccentric cam 29 over the second half cycle pullslink lever 35 to the right thereby rocking, via release lever 38 andshaft 13, the carriage return clutch actuator arm 39 clockwise therebyto effect disengagement of the carriage return clutch 46. The clockwisemovement of the actuator arm brings the reset fiat 58 on the cam 54 intoengagement with a reset abutment 78 which resets the cam to its normalFIGURE 1 position.

The time interval between engagement of a margin stop 73 with thelocator 74, and disengagement and immediate re-engagement of thecarriage return clutch 46, as when a repeat line space is required,being generally shorter than the recovery time of the platen indexingmechanism, requires as hereinbefore stated that an engagement delay beprovided to assure recovery before re-engagement. This is accomplishedby the roll cam 54 which permits a constant predictable time period toelapse between the first contact of the roll cam 54 and frictioncylinder 56 and engagement of the clutch spring 52 by the drag block 45.In addition the dynamics of the actuator arm 39 and drag block 45 aredeterminable by the shape of the cam 54 so as to accurately control theengagement characteristics of the wrap spring 52 by eliminating actuatorarm bounce and by reducing the shock of instantaneous carriage returnclutch engagement by permitting a gradual pickup of load by the clutchspring 52.

It should be understood that the foregoing disclosure relates to only apreferred embodiment of the invention and that it is intended to coverall changes and modifications of the example of the invention hereinchosen for the purposes of the disclosure which do not constitutedepartures from the spirit and scope of the invention.

The invention claimed is:

1. In a clutch having driving and driven members,

operation responsive means movable to effect the coupling of saiddriving and driven members,

and means associated with said driving member and said operationresponsive means to control the movement of said operation responsivemeans comprising, a friction cylinder driven by said driving member,

and an eccentric roll cam pivotally mounted on said operation responsivemeans operative upon movement thereof to encounter said frictioncylinder thereby to delay the movement of said operation responsivemeans.

2. In a clutch having drive and driven members and a coil springoperative when wrapped to couple said drive and driven members,

an actuator arm provided with spring engagement means operative toeffect wrapping of said spring,

a friction cylinder driven with said drive member,

and an eccentric roll cam rotatably mounted on said actuator arm adaptedto encounter said friction cylinder before said spring engagement meansto thereby delay the operation of said spring engagement means.

3. In a wrap spring clutch, a driving element and a driven element,

a wrap coil spring driven by said driving element and adapted to wrapabout said driven element to couple, said driving and driven elements,

a friction sleeve mounted on said driving element,

a clutch engagement actuator arm,

a drag block on said arm adapted upon movement of said actuator arm tofrictionally engage said spring whereby it will wrap,

and an eccentric roll cam rotatably mounted on said actuator arm adaptedto engage said friction sleeve and to be driven thereby whereby theengagement of the drag block with said spring is delayed a predeterminedtime.

4. In a typewriter having a carriage and a platen rotatably mountedthereon,

platen indexing mechanism operable through a working interval incidentto powered carriage movement and through a recovery interval aftertermination of powered carriage movement,

a rotatable drum,

a carriage return drawband connected to said drum and to said platenindexing mechanism, power means,

a carriage return clutch engageable in response to depression of a drumreturn key for coupling said power means to said carriage thereby inturn operating said platen indexing mechanism through its workinginterval and returning said carriage, and disengageable in response tomovement of a margin locator by said carriage, the interval betweendisengagement and re-engagement of said clutch incident to repeatoperation of said carriage return key being less than the recoveryinterval of said platen indexing mechanism,

means movable to effect clutch engagement in response to carriage returnkey depression,

and control cam means operative in response to and for predeterminedlycontrolling the movement of said last named means to thereby delayclutch engagement over an interval greater than the recovery interval ofsaid platen indexing mechanism.

5. In a typewriter having a carriage and a platen rotatably mountedthereon,

platen indexing mechanism.

a rotatable drum,

a carriage return drawband connected to said drum and to said platenindexing mechanism, power means,

a clutch for coupling said power means to said drum thereby in turn tooperate said indexing mechanism and to return said carriage,

clutch actuator means,

means responsive to depression of a carriage return key to effect themovement of said clutch actuator means to effect clutch engagement andresponsive to terminal movement of said carriage against a marginlocator for moving said clutch actuator means to effect clutchdisengagement, the improvement comprising a friction cylinder driven bythe driving element of said clutch and an eccentric roll cam on saidclutch actuator means adapted upon movement of said clutch actuatormeans to effect clutch engagement to encounter said friction cylinder tothereby delay the movement of said clutch actuator means whereby clutchengagement is delay-ed over an interval greater than the recoveryinterval of said platen indexing mechanism.

References Cited by the Examiner UNITED STATES PATENTS 1,266,550 5/1918Carroll 192-81 X 2,104,559 1/1938 Hillis 197-65 X 2,395,763 2/1946Sagner 197-120 X 2,566,539 9/ 195 l Starkey.

2,567,937 9/1951 Hart 197-66 2,729,322 1/1956 Kloski 197-66 2,915,15812/1959 Smith 192-81 2,930,463 3/1960 Dodge et al 192-81 2,954,1089/1960 Lenney 192-81 3,095,071 6/ 1963 Mason.

ROBERT E. PULFREY, Primary Examiner.

E. T. WRIGHT, Assistant Examiner.

1. IN A CLUTCH HAVING DRIVING AND DRIVEN MEMBERS, OPERATION RESPONSIVEMEANS MOVABLE TO EFFECT THE COUPLING OF SAID DRIVING AND DRIVEN MEMBERS,AND MEAND ASSOCIATED WITH SAID DRIVING MEMBERS AND SAID OPERATIONRESPONSIVE MEANS TO CONTROL THE MOVEMENT OF SAID OPERATION RESPONSIVEMEANS COMPRISING, A FRICTION CYLINDER DRIVEN BY SAID DRIVING MEMBER, ANDAN ECCENTRIC ROLL CAM PIVOTALLY MOUNTED ON SAID OPERATION RESPONSIVEMEANS OPERATIVE UPON MOVEMENT THEREOF TO ENCOUNTER SAID FRICTIONCYLINDER THEREBY TO DELAY THE MOVEMENT OF SAID OPERATION RESPONSIVEMEANS.